Sir A.J. Ayer, in full Sir Alfred Jules Ayer (born October 29, 1910, London, England—died June 27, 1989, London), British philosopher and educator and a leading representative of logical positivism through his widely read work Language, Truth, and Logic (1936). Although Ayer’s views changed considerably after the 1930s, becoming more moderate and increasingly subtle, he remained loyal to empiricism, convinced that all knowledge of the world derives from sense experience and that nothing in experience justifies a belief in God or in any other extravagant metaphysical entity. His logical views alone, expressed in an elegant, crystalline prose, would have ensured him a place in the history of modern philosophy. But Ayer, playful and gregarious, was also a brilliant lecturer, a gifted teacher, and a successful broadcaster, as ready to offer his opinions on politics and sports as on logic and ethics. Named a fellow of the British Academy in 1952 and knighted in 1970, he became one of the most influential British philosophers of the 20th century.

Early life

Although Ayer was raised in London, both his father, a French Swiss businessman, and his mother, a Dutch citizen of Jewish ancestry, were born abroad, and Ayer grew up speaking French fluently. An extremely able, though sensitive, boy, he won a scholarship to Eton College (1923), where he excelled in classics but had no opportunity to study science, an omission that he would always regret. In 1929 he won a classics scholarship to the University of Oxford, where he also studied philosophy. His tutor, Gilbert Ryle (1900–76), soon described Ayer as “the best student I have yet been taught by.” While at Eton, Ayer had read essays by Bertrand Russell (1872–1970), one of which, “On the Value of Scepticism” (1928), proposed a “wildly paradoxical and subversive” doctrine that Ayer would adopt as a lifelong philosophical motto: “It is undesirable to believe a proposition when there is no ground whatever for supposing it true.” At Oxford, Ayer studied A Treatise of Human Nature (1739) by the radical empiricist David Hume (1711–76) and discovered the recently published Tractatus Logico-Philosophicus (1921) by Ludwig Wittgenstein (1889–1951). Instinctively irreverential, he used both works to attack the conventionally religious, socially conservative figures who then dominated philosophy at Oxford.

Having secured a fellowship at the college of Christ Church, Ayer spent part of 1933 in Vienna, where he attended meetings of the Vienna Circle, a group of mostly German and Austrian philosophers and scientists who were just then beginning to attract the attention of philosophers in England and the United States. Although Ayer spoke poor German and was hardly able to take part in the discussions, he became convinced that the doctrine of logical positivism that the group was developing marked an important advance in the empiricist tradition, and he returned home an ardent convert. Within two and a half years he had written a manifesto for the movement, Language, Truth, and Logic.

In this work, following Wittgenstein and the members of the Vienna Circle, Ayer defended a verificationist theory of meaning (also called the verifiability principle), according to which an utterance is meaningful only if it expresses a proposition the truth or falsehood of which can be verified (at least in principle) through experience. He used this theory to argue that metaphysical talk about God, the cosmos, or “transcendent values” was not merely, as earlier empiricists had maintained, excessively conjectural but literally meaningless. Ayer’s specific contribution was to develop this argument with unusual clearheadedness and rigour, showing how statements about the external world, other minds, and the past could be accorded sense through an analysis in verificationist terms. His argument that statements of moral evaluation, because they are unverifiable, are not descriptions of fact but merely “emotive” expressions of feeling aroused particular controversy.

Language, Truth, and Logic eventually became one of the best-selling works of serious 20th-century philosophy. Despite his obvious abilities, however, Ayer could not secure a permanent teaching position at Oxford—a fact that increased his hostility toward the philosophical establishment there.

Although Ayer claimed that Language, Truth, and Logic answered all major philosophical questions, the problems he had so confidently “solved” soon came back to haunt him. In a series of important papers and a book, The Foundations of Empirical Knowledge (1940), he wrestled with critics who doubted that all meaningful discourse could be analyzed in terms of sense experience. In particular, he turned for the first time to a careful analysis of the “sense-data” that empiricists had always claimed were the basis of all real knowledge. In a characteristic move, Ayer now contended that sense-data should be understood not as part of the furniture of the world but as conceptual constructs, or logical fictions, that allow one to distinguish between sensory experience and matter and between appearance and reality.

In the years surrounding the publication of Language, Truth, and Logic, philosophy had to compete with more pressing concerns. Like many young men of the period, Ayer was critical of what he saw as the British government’s do-nothing approach to the rise of unemployment at home and of fascism abroad. After briefly considering joining the British Communist Party, Ayer instead joined the Labour Party. An early and forthright critic of Neville Chamberlain’s policy of appeasement, Ayer volunteered for the Welsh Guards as soon as war broke out. After completing officer training, he joined an intelligence unit, eventually becoming a specialist on France and the French Resistance and gaining the rank of major. His war assignments took him to New York, to Algeria, and, after the liberation of France, to the southern part of that country and to Paris.

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